Revert "Bluetooth: btusb: add sysfs attribute to control USB alt setting"

This reverts commit b16b327e.

The sysfs node introduced by this patch could potentially race with user
space. The original motivation - Support configuring altsetting from the
user space will be added by another series.

Cc: chromeos-bluetooth-upstreaming@chromium.org
Signed-off-by: Hsin-chen Chuang <chharry@chromium.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>